Rotary transforming apparatus.



No. 717,359. Patented Dec. 30.1902.

A. a. DAVIS.

ROTARY TBANSFORIIING APPARATUS.

(Application filed May 26, 1900.)

(No Model.) --2 Sheets-Sheet I;

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10. 1 '11 15 15 1a rm m JJJflJJJ 4 12 J JJ \/rrflzsszs. 'pR/EHTUIQ- A. HM} 45 2 Nq. M7359. Patented Dec. 30, I902.

A. G. DAVIS.

ROTARY. TRANSFOBMING APPARATUS.

(Application filed May 26, 1900.) (R0 ModeI 2 Sheets-Sheet 2.

\A/I HEEEES. 'lhh/ EplTlI llil UNITED STATES PATENT OFFICE.

ALBERT G. DAVIS, OF SCHENECTADY, NEW YORK, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ROTARY TRANSFORMING APPARATUS.

SPECIFICATION formingpart of Letters Patent No. 717,359, dated December 30, 1902.

Application filed May 26, 1900.

To ctZZ whom it may concern.-

Be it known that I, ALBERT G. DAVIS, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Rotary Transforming Apparatus, (Case No. 959,) of which the following is a specification.

My invention relates to transforming or converting devices of the class designed to interchangeably transform direct and alternating current, and has for its object a converter which shall not only perform the function above set forth, but shall also be capable of any desired ratio of transformation.

In carrying out my invention in practice I make use of primary and secondary windings assembled upon a core of such nature that the magnetic circuits passing through one set of windings are completed through portions of the core upon which is wound the other set of windings. By such an arrangement the portions of the core common to one set of windings form return-circuits for the other portions of the core about which the other set of windings is placed.

In its details and mode of application my invention will be better understood by reference to the following description, taken in connection with the accompanying drawings, while its novel features will be particularly pointed out in the claims appended hereto.

Figure 1 represents a transforming apparatus having its primary and secondary windings fixed, while Fig. 2 is a modification showing an arrangement in which the said windings are mounted on a movable member of the machine.

In Fig. 1 the primary and secondary windings are carried by a core structure consisting of two concentric rings connected by radial arms. The outer ring is indicated at 1, the inner ring at 2, and the radial connectingarms at 3. In the particular structure shown the two concentric rings are connected by means of six radial arms, upon each of which is arranged a primary winding, (indicated by the reference-numeral 4.) Diametrically opposite windings are connected in series with each other, with three of the free terminals joined to a common point 5 and the remain- Serial No, 18,045. (No model.)

ing terminals to a three-phase supply-circuit, (indicated at 6, 7,and 8.) These primary windings being excited by three-phase current conveyed over the lines 6, 7, and 8 set up threephase magnetic fluxes which traverse the outer ring 1 and the cores upon which the windings are placed and complete their magnetic circuits through the inner ring 2, upon which is placed a continuous secondary winding 10, connected at intervals in its length to a commutator 11. The three-phase fluxes set up by the action of the primary excitingwindings 4 cause a progressive shifting of the resultant field of force acting in the ring 2. Mounted within the influence of this rotating field of force is a revolving field structure 12, movable about an axis centrally located with respect to the core 2. This revolving field structure is provided with exciting windings 13, receiving current eitherfrom the brushes 14 or from the collector-rings 15, the current being derived from the brushes when the machineis used to convert alternating current into direct current and from the collectorrings when the machine is supplied with direct current to be converted into alternating current. In either of these cases the excitingwindings 13 being supplied with direct current gives rise to a fixed polarity in the core 12, which thereupon looks into fixed relation with the rotating field acting in the core 2, thereby producing a synchronous rotation of the field-magnet structure, indicated at 12. The brushes 14, which bear upon the commutator 11, are carried in fixed relation with the field-magnet structure and either deliver or receive'direct current,depending upon whether the machine converts direct current to alternating or the reverse. To secure a variable ratio of transformation, means may be provided for varying the ratio of turns in the primary and secondary windings. This may be conveniently accomplished by subdividing either set of windings and then connecting in circuit the desired amount of such windings. In Fig. 1 the switches 33 and c0- operating contacts 34, connected to points inthe windings 4, illustrate an application of this idea.

The arrangement shown in Fig. 2 differs from that in Fig. 1 in that the member carrying the primary and secondary coils or windings is arranged to rotate, while the fieldmagnet structure is stationary. In this form of apparatus the primary and secondary windings are placed upon a structure consisting in this particular instance of a single ring supported upon or carried bya plurality of arms radiating from a central mass of magnetic material. Supposing the machine to be converting alternating current into direct current, then the windings which would operate as primary windings are indicated at 16, while the secondary winding wound upon the ring-core 17 is indicated at 18. The cores supporting the windings 16 are shown at 19 and extend inwardly to a mass of material 20, through which passes the shaft 21. Similarly to the arrangement in Fig. 1, the continuous winding 18 is provided with a commutator 22 of any suitable form, upon which bear fixed brushes 23, connected to direct-current mains 24. The inner ends of the windings 16 are connected to a common point 25, while their extremities make connection with the external alternating-current system through collector rings and brushes, (indicated at 26,) the alternating-current mains being shown at 27, 28, and 29. The pole-pieces of the fixed fieldmagnet structure are indicated at 30 and 31. As in other synchronously-operating rotary converting devices, the field-magnet structure is excited by direct current derived from any suitable source, and generally from the device itself. As Fig. 1 illustrates a suitable means for exciting the field structure with direct current, it is unnecessary to indicate such a means in connection with Fig. 2.

In order to confine the lines of force to the magnetic circuits provided for them and to prevent leakage of the same across intervening air-spaces, I may make use of conducting-shields which act to oppose or beat back the lines of force tending to penetrate them. The arrangement of shields of this character is indicated in Fig. 2 at 32. These shields are somewhat sector-shaped in cross-section and fit within a space bounded by the opposing surfaces of the windings 16 and 18 and by a well-known mode of operation act to prevent a leakage of lines of force across this space. It will be noted that since the lines of force due to coils wound upon adjacent radial projections complete their magnetic circuit through the same portion of the connecting circular core the resulting flux in this portion of the connecting-core must depend upon the resultant action of the fluxes in the radial cores. It follows that the fluxes in the ring-cores are displaced in phase from those in the radial cores, the relation of fluxes in the ring-core being indicated in a threephase system by the three sides of a triangle, while that of the fluxes in the radial cores correspond to lines extending from a point within the area of the triangle to the vertices of the triangle.

What I claim asnew, and desire to secure by Letters Patent of the United States, is-

1. In a transforming device for interchangeably transforming alternating and direct current, a plurality of magnetic circuits, alternating-current windings in inductive relation to said circuits, a common return for the magnetic circuits, a winding in fixed relation to the common return, and a commutator connected to the last-mentioned winding.

2. In a transforming device for interchangeably transforming alternating and direct current, a plurality of branch magnetic circuits, alternating-current windings in inductive relation to said circuits, a common return for the magnetic circuits and a direct-current winding in fixed relation to the common return, a commutator connected to the directcurrent winding, brushes bearing on said commutator, and means for causing relative rotation between the brushes and commutator.

3. In a transforming device, a ring-core, a continuous winding thereon, sources of multiphase fluxes in operative relation to the core, an unwound return-path for the fluxes outside the core, and a revolving field structure within the influence of said fluxes.

4. Branch magnetic circuits, high-tension multiphase alternating-current windings on the branches, a common return for the magnetic circuit, a low-tension winding on the return, and a commutator and brushes in cooperative relation to the low-tension winding.

5. The combination ofaring-core, branches extending therefrom and connected together, windings on the ring-core and also on the branches, means for changing the number of active turns of one of said windings, and a commutator connected to another of said windings.

6. In a transforming device, a ring-core, a winding thereon, sources of multiphase fluxes in operative relation to the winding, and a shield or shields for preventing leakage of lines of force either to or from said ring-core.

In witness whereof I have hereunto set my hand this 23d day of May, 1900.

ALBERT G. DAVIS.

Witnesses:

BENJAMIN B. HULL, MABEL E. J ACOBSON. 

